PHP - consulta de gropu by

<?php

$conexion=mysqli_connect("localhost","root","","anco")or die ("error");

$registro=mysqli_query($conexion,"select count(emp.cod_emp) as

cantidad,Nom_emp,Nom_cli,detalle_det from detalle_boleta as bol

inner join clientes as cli on cli.cod_cli=bol.cod_cli

inner join empleados as emp on emp.cod_emp=bol.cod_emp group by(bol.cod_emp)") or die

("error".mysqli_error($conexion));

	while($reg=mysqli_fetch_array($registro))

	{

		echo $reg["cantidad"]."<br>";

		echo $reg["Nom_emp"]."<br>";

		echo $reg["Nom_cli"]."<br><br>";

	}

mysqli_close($conexion);

?>

select count(*) as cantidad, Nom_emp, Nom_cli

from detalle_boleta as bol

inner join clientes as cli on cli.cod_cli=bol.cod_cli

inner join empleados as emp on emp.cod_emp=bol.cod_emp

group by Nom_emp, Nom_cli